Baseball commissioner Bud Selig isn't sure when a blood test for human growth hormone will be used in the minor leagues. Selig said Monday that scientific experts haven't been able to give him a time frame for their conclusions. "I want them to come back and tell me what this means, and they already have said they can't do it right now, so there's no sense in me speculating, because I don't know," Selig said. "They've got a lot of work to do to determine the authenticity of it." Selig can start blood testing on players with minor league contracts at any time. Testing on players on 40-man major league rosters is limited to urine, and rules can't be changed without an agreement with the players' association.